Heat-sensitive stencil sheet

ABSTRACT

A HEAT-SENSITIVE STENCIL SHEET WHICH CONSISTS OF A POROUS THIN SUPPORTING PAPER AND A FILM CONSISTING OF A THERMOPLASTIC RESIN AND AFFIXED TO ONE SURFACE OF SAID SUPPORTING PAPER WITH AN ADHESIVE, SAID ADHESIVE CONTAINING A VISIBLY REACTIVE HEAT-SENSITIVE COMPONENT; AND A HEAT-SENSITIVE STENCIL SHEET WHICH CONSISTS OF A POROUS THIN SUPPORTING PAPER, A FILM CONSISTING OF A THERMOPLASTIC RESIN AND AFFIXED TO ONE SURFACE OF SAID SUPPORTING PAPER WITH AN ADHESIVE, AND A COATING COMPRISING A VISIBLY REACTIVE HEATSENSITIVE COMPONENT AND PROVIDED ON THE SURFACE OF SAID THERMOPLASTIC RESIN FILM.

United States Patent 3,682,763 HEAT-SENSITIVE STENCIL SHEET Keishi Kubo, Yokohama-shi, and Kiyoshi Sakai, Tokyo, gapan, assignors to Kabushiki Kaisha Ricoh, Tokyo, apan No Drawing. Filed Dec. 3, 1969, Ser. No. 881,880

Claims priority, application Japan, Dec. 20, 1968, 43/ 93,085 Int. Cl. B41n 1/24, 15/00 US. Cl. 161- -159 6 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION (a) Field of the invention The present invention relates to a heat-sensitive stencil sheet prepared by affixing a film consisting of a thermoplastic synthetic resin to the surface of a porous thin supporting paper. More particularly, it relates to a heat sensitive stencil sheet for use in mimeographic printing, which is capable of presenting colored images in the perforated area thereof and observable in the process of perforation.

(b) Description of the prior art It is known to prep-are a heat-sensitive stencil sheet, viz, the so-called stencil sheet, by employing a porous thin paper weighing 7-15 g. per square meter, which is made of a natural fiber obtained from mitsumata,. paper mulberry, manila hemp, etc. or a synthetic fiber mainly consisting of rayon, polyvinylalcohol, terphthalate polyester resin, acrylic resin or the like, and afiixing to its surface a film of about -10,u. thick consisting of a thermoplastic synthetic resin such as polystyrene, polypropylene, polyethylene and vinylidene chloride-vinyl chloride copolymer. When a stencil is prepared by employing such a stencil sheet, the original carrying the desired image is superposed upon the film of the stencil sheet, and said original is irradiated with electro-magnetic waves including infrared rays, thereby effecting perforation of the portion of said film corresponding to the image area of the original closely contacted therewith.

In said perforating operation, the amount of irradiation (viz, the amount of exposure) with electro-magnetic Waves including infrared rays has a remarkable influence upon the clearness of the perforated image on the stencil obtained thereby. When the amount of irradiation with electro-magnetic waves including infrared rays is too small, the perforation of the stencil obtained therefrom is defective, resulting in an indistinct printed image when said stencil is used for printing, while when the amount ice of irradiation with electro-magnetic waves involving infrared rays is too much, the perforation of the stencil is excessive as compared with the original image, resulting in an indistinct printed image. However, inasmuch as said heat-sensitive stencil sheet of the prior art has been prepared by aflixing an extremely thin film to a thin paper as described above, it has been extremely diflicult to judge by observation with the unaided eye whether or not the perforated image on the stencil was formed properly. Accordingly, it has also been difficult to determine the appropriate amount of irradiation with electro-magnetic waves including infrared rays to use to obtain a properly developed image. Such being the case, under the existing circumstances, the foregoing judgment or determination of the amount of irradiation with infrared rays to use is made on a trial-and-error basis, that is, the approximate proper amount of exposure is estimated by actually preparing stencils from said stencil sheet, putting them to use for mimeographic printing, and comparing the images formed on the thus obtained prints with that of the original.

SUMMARY OF THE INVENTION The object of the present invention is to provide a heat-sensitive stencil sheet which makes it possible to easily determine the amount of exposure appropriate for preparing a stencil therefrom, or makes it possible to judge, by observation with the unaided eye, the appropriateness of the perforation being eifected.

The present invention comprises two embodiments, namely (A) a stencil sheet consisting of a porous thin supporting paper and a film consisting of a thermoplastic synthetic resin and afiixed to one surface of said supporting paper with an adhesive, said adhesive containing a visibly reactive heat-sensitive component, and (B) a stencil sheet consisting of a porous thin supporting paper and a thermoplastic synthetic resin film afiixed to one surface of said supporting paper with an adhesive, wherein the surface of said thermoplastic synthetic resin film is provided with a coating comprising the foregoing visibly reactive heat-sensitive component.

It is to be noted that said visibly reactive heat-sensitive component utilized for the present invention and to be elucidated later in the present specification refers to a compound or composition which has been generally employed for a copying material capable of printing by means of irradiation with infrared rays alone, viz, the so-called heat-sensitive copying material.

As to the adhesives to be employed for the stencil sheet according the present invention, any of those conventional adhesives which have hitherto been popular are applicable, and especially an adhesive comprising vinyl acetate polymer as its principal component, and an adhesive comprising acrylic resin as its principal component, etc. are suitable. The commercial adhesives of this category include, for instance, an adhesive manufactured by Nippon Synthetic Chemical Industry Co., Ltd. and sold under the trade name Gohsenyl M-50 Y-S, which comprises a vinyl acetate homopolymer having a polymerization degree of about 1100 and dissolved in methanol, an adhesive manufactured by Kureha Chemical Industry Co., Ltd. and sold under the trade name Krehalon-SN, which comprises vinylidene chloride acrylom'trile copolymer dissolved in a solvent, an adhesive manufactured by Nissetsu Industry Co., Ltd. and sold under the trade name Super Dain PB-85, which comprises acrylic resin dissolved in alcohol, etc. As to the porousthin supporting paper and the thermoplastic resin film, both the aforesaid conventional thin paper and films are applicable, but a film comprising vinylidene chloride-vinyl chloride copolymer as its principal component is particularly suitable.

-In a stencil sheet according to embodiment (A) of the present invention, the foregoing adhesive is made to contain a compoundcapable of de'veloping a color by heating. In this respect, inasmuch as the resin to be employed as the adhesive to afiix the porous thin supporting paper and thefilm is generally dissolved in alcohol and is in the state of a solution, said visibly reactive heat sensitive component to be mixed in said solution desirably also is soluble in alcohol. But, a visibly reactive heat-sensitive component which is insoluble in alcohol is of course applicable, provided that it can be mixed in the adhesive as fine particles, that is, to form a suspension. In this connection, said component is desired to be capable of developing a color by heating at a temperature in the range of l20-170 C. at which the phenomenon of perforation of the film maybe accomplished by the irradiation with infrared rays. In other words, in a stencil sheet according to the present invention, it is required that, when an original is superposed on said stencil sheet and the irradiation with infrared rays is then performed a colored visible, image reproducing the image of the original is formed in the layer of adhesive simultaneously with the perforation of the film affixed to the surface of said stencil sheet. Accordingly, it is desirable that the visibly reactive heat-sensitive component not only be uniformly contained in said layer of adhesive, but also be capable of developing the color within a thermal range close to or congruent with the thermal range at which the perforation takes place. As to the amount of said visibly reactive heat-sensitive component to be contained in the adhesive, it is not necessary to make its concentration so high as that employed for the colordeveloping, heat-sensitive layer of a heat-sensitive copying material, but it suflices to employ it at the rate of at least 0.3 part by weight per 1 part by weight of the adhesive, and, when said component exceeds 4 parts by weight per 1 part of the adhesive the perforation efficiency of the stencil sheet is impaired. When the foregoing adhesive containing a visibly reactive heat-sensitive component is employed for aflixing a porous thin supporting paper to a film as above to the extent of making the coated amount be at least 1.5 g. per square meter, in terms of the solid content thereof, it not only serves to form a colored visible image and affix the thin supporting paper and the film' as stated above, but also facilitates the determination of an appropriate amount of the irradiation with infrared rays to use. It is to be noted, however, that the employment of said adhesive in excess of g. per square meter for the foregoing coating purpose is inadvisable as it will impede the perforation efiiciency of the stencil sheet.

As for a stencil sheet according to embodiment B) of the present invention, it is prepared either (1) by the steps. of coating a solution of the aforesaid visibly reactive heat-sensitive component prepared by dissolving or dispersing it in an appropriate solvent such as alcohol alone, a mixed solution of alcohol and ether and amixed solution of alcohol and keto alcohol onto the surface of film layer of the stencil sheet prepared in advance by aflixing a film onto a porous thin supporting paper with an adhesive, thereby on the film a coating of a visibly reactive heat-sensitive component, or (2) by the steps of coating a solution of said component onto one surface of the film, thereby forming a coating of said component on said film, and subsequently affixing a porous thin supporting paper onto the non-coated surface of said film with an adhesive.

The suitable amount of said solution of a visibly reactive heat-sensitive component to be coated onto the surface of said film is in the range of 0.5 g./m. to 10 g./rn. in terms of solid content thereof, and When the coated amount deviates from said range, a proper judgment of exposure and the perforation efliciency may be hampered thereby. Further, as the solvent for use in applying said coating of a visibly reactive heat-sensitive component onto the surface of the film, there can be used alcohols such as ethanol, n-propanol, n-butanol and 2-ethylbutyl alcohol, ethers such as ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, ethyleneglycolmonobutyl ether and diethyleneglycol-monoethyl ether, and keto alcohols such as diacetone alcohol, The visibly reactive heat-sensitive component may be applied to said surface of the film in the form of a' solution prepared by dissolving or dispersing it-together with a small amount of an adhesive for use in aflixing the porous thin supporting paper to said film-4n the foregoing solvent. When the visibly reactive heat-sensiti ve component is thus applied to the surface of film in the form of a solution containing an appropriate solvent and/or an adhesive, the surface of the film is somewhat eroded by the solvent or the solvent-containing adhesive, thereby causingfislarild component to be bonded firmly onto the surface of In the stencil sheet according to the present invention in the two embodiments described above there is no necessity for strictly adhering to the aforesaid range with respect to the amount of a visibly reactive heat-sensitive component applied to the surface of film and the amount of the component mixed or dissolved in the adhesive. However, when said amount is less than the foregoing minimum, the clarity of the image formed in the perforated area may not be sufficient to determine an appropriate amount of exposure at the time of preparing the aforesaid stencil. On the other hand, when said amount of the component exceeds the foregoing maximum, namely 1O g./m. (in terms of the coated amount of the component), a satisfactory formation of images to be employed as the criteria for effecting a proper perforation is infeasible.

Next, as to said visibly reactive heat-sensitive component applicable to the present invention, a variety of suitable components are mentioned in the literature pertaining to the heat-sensitive copy material and the like. But, of the known compounds, those which are suitable for the present invention are enumerated in the following:

(a) Complex compounds which change color at a temperature range between from 50 C. to 120 C. These complex compounds are described in Japanese patent publication No. 14509/1966 (applicant: Kabushiki Kaisha Ricoh), and include such complex compounds as, for example,

hexamethylenetetramine.cobalt chloride (CoCl 2C H N IOH O yellow-red hexamethylenetetramine-nickel chloride (light green), hexamethylenetetramine-nickel bromide (light green), hexargrethylenetetramine-cobalt nitrate or cobalt sulfate hexamethylenetetramine-nickel nitrate or nickel sulfate.

(b) A composition of matter which consists substantially of a compound having secondary alcoholic hydroxyl radical and. a melting point ranging from -180 C., sulfur and metal-inorganic salt or metal-acetate.

Various compositions of matters are described in Japanese patent publication No. 14510/1966 (applicant: Kabushiki Kaisha Ricoh).

As for the compounds having secondary alcoholic hydroxyl radical, there are benzoin compounds such as benzoin, 2-methoxybenzoin, 4-chlorobenzoin, 4-dimethylaminobenzoin and 2-chloro-4'-dimethylaminobenzoin, carbinols such as diphenylcarbinol, phenolic compounds such as resorcin, pyrogallol, 3-hydroxytoluene-4-sulphonic acid, 4-nitro-resorcin and 4,6-dibromoresorcin, aliphatic polyhydric alcohols such as erythritol, sorbitol, galactose, maltose, mannitol and saocharose.

As for the metal inorganic salts and metal-acetates, there are compounds producing colored-sulfide compounds by reaction of sulfur and include, for example, sulfates, nitrates carbonates and acetates of copper, lead, tin, molybdenum, cobalt, chromium, nickel, manganese, titanium, antimony, rhodium, mercury, iron, barium, bismuth, arsenic, magnesium, indium and iridium.

(c) A composition of matter which consists substantially of a compound selected from the compounds having secondary alcoholic hydroxyl radical described in the aforesaid (b) sulfur and a complex compound described in the aforesaid (a). These compositions of matter are described in Japanese patent publication No. 14511/1966 (applicant: Kabushiki Kaisha Ricoh).

(d) A composition of matter which consists substantially of a carbohydrate and a dehydrating agent. These compositions of matter are described in Japanese patent publication No. 13237/ 19-67 (applicant: Kabushiki Kaisha Ricoh). There are described various compositions of matter in the aforesaid publication, for example, saccharose, fructose, galactose and. starch as the carbohydrate, and sulfuric acid, acetic acid anhydride, zinc chloride anhydride and P-toluenesulfonic acid as the dehydrating agent. 1

As for the compounds or the compositions which can develop visible color by heat treatment, the various compounds and the combinations of the compounds are also known in addition to the aforesaid compounds and the compositions of matter as follows.

(e) A composition of matter which comprises an iron salt of a fatty acid having a long chain such as ferric stearate and ferric myristate and phenol or phenolic compound such as tannic acid, gallic acid and ammonium salicylate. I

(f) A composition of matter which consists substantially of a heavy metal salt of an organic acid such as nickel, cobalt, lead, copper, iron, mercury and silver salts of acetic, stearic and palmitic acids and an alkaline earth metal sulfide such as calcium-, strontiumand barium sulfides. And, a composition of matter which consists substantially of the aforesaid heavy metal salt of organic acid and an organic chelate compound such as S-diphenylcarbazide and diphenylcarbazone.

(g) A composition of matter which consists substantially of a heavy metal oxalate such as silver, lead, mercury and thorium oxalates and a sulfur-containing compound such as sodium-tetrathionate, sodium thiosulfate and thio-urea.

(h) A composition of matter which consists substantially of a ferric salt of a fatty acid such as ferric stearate and an aromatic polyhydroxyl compound such as 3,4-dihydroxytetraphenylmethane. I

(i) A composition of matter which consists substantially of a noble metal salt of an organic acid such as silver oxalate and mercury oxalate and an organic polyhydroxyl compound such as polyhydroxyalcohol, glycerin and glycol.

(j) A composition of matter which consists substantially of a noble metal salt of an organic acid such as silver behenate and silver stearate and a reducing agent of an aromatic compound such as protocatechuic acid, spiroindane and hydroquinone.

(k) A composition of matter which consists substantially of an iron salt of a fatty acid such as ferric pelargonate and ferric laurate and thiosemicarbazide or isothiosemicarbazide derivative.

(1) A composition of matter which consists substantially of a lead salt of an organic acid such as lead caproate, lead pelargonate and lead behenate and thiourea 6 derivative such as ethylenethiourea and N dodecylthiourea.

(m) A composition of matter which consists substantially of a heavy metal salt of a higher fatty acid such as ferric stearate and copper stearate and zinc-dialkyldithiocarbamate.

(n) A composition of matter which forms an oxazine dye such a combination as resorcinol and nitroso compound, or a composition matter which forms an azo dye.

However, the visibly reactive heat-sensitive component applicable to thepresent invention is not necessarily limited to such components are described as above, but any of such components as will thermally liberate polyvalent metal cation and are generally used in the field of the heat-sensitive copying, e.g. the above-mentioned heavy metal salt of an organic acid or a compound prepared by combining the organic reducing agent, sulfur compound or amino compound with a heavy metal salt of an organic acid and such a single compound as will thermally develop a color is of course applicable.

When a stencil is prepared by irradiating a stencil sheet of the present invention employing the visibly reactive heat-sensitive component as above with electromagnetic waves including infrared rays, simultaneously with the perforation effected in the portion of the film corresponding to the image area of the original, the component existing on the perforated portion of the film is colored, and the colored melt congregates in a concentrated fashion on the edge of said perforated portion, whereby there can be observed a distinct image having a sharp outline consisting of perforations. Besides, the extra-fine particles of said colored melt adhere to the fibers of the porous thin supporting paper, whereby the perforated portion can be observed with the unaided eye as clearly as ordinary prints, characters or photographs. That is, the visibly reactive heat-sensitive component forms the colored melt during the process of melting and perforation of the film, said colored melt congregates in a concentrated fashion onto the outline of the perforated image area and adheres onto the bare fibers of the porous thin supporting paper that have been exposed by said perforation, and, as a result, an image observable with the unaided eye is formed. Accordingly, the perforated portion in this case does not impair the permeability of a printing ink.

As for the application of an adhesive containing the visibly reactive heat-sensitive component, in preparing the foregoing stencil sheet according to the present invention, it may be coated onto either 1) the porous thin supporting paper or (2) the film, and the aflixing of said porous thin paper and the film may be effected in the conventional manner. Further, said coating of the adhesive the application of the visibly reactive heat-sensitive component onto the surface of film can be performed by the roll coating method, spray method and so on.

Preparation of a stencil from the stencil sheet according to the present invention as described above is accompanied by such advantages that not only is it possible to determine the appropriate amount of infrared-ray irradiation so that the perforated area of said stencil can be easily observed and compared with the original image with the unaided eye, but also the clearness of the image on the prints to be obtained through printing by employing said stencil can beforeseen from the clarity of the colored visible image formed onto the stencil actual printing, the re areobtained prints that have clarity equivalent to that of the image formed onto the stencil. According to the present invention, therefore, the defect of the conventional stencil sheet, namely, that the appropriateness of an amount of infrared-ray irradiation employed may be judged only through actual preparation of a stencil therefrom and putting it to printing use, can be overcome.

7 DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 8 g. of saccharose was dissolved in 7 CC'."Of water, and into a solution thus obtained were added and dissolved cc. of methanol and 8 g. of paratoluene sulforiic acid, whereby a solution of visibly reactive heat-sensitive component was prepared.

' By mixing (1) a resinous adhesivesolution, whichfwas prepared'by employing a manufacture of Nippon Synthetic Chemical Industry Co., Ltd. sold under the trade name Gohsenyl M-50 Y-S) (a 50% methanol solution comprising vinyl acetate homopolymer whose polymerization degree is 1100) and adjusting its'viscosity'to be 10 centipoises with (2) methanol, with its equivalent of the foregoing solution of visibly reactive heat-sensitive component, an adhesive containing a visibly reactive heat-sensitive component was prepared. Subsequently, a 7 .-thick transparent film comprising vinylidene chloridevinyl chloride copolymer as its principal component and a 30/L'thlCk porous thin supporting paper comprising manila hemp fibers as its principal component and weighing 10 g. per square meter were afiixed together by employing the foregoing adhesive.

The application of said adhesive on this occasion was effected by a roll coating method in such a manner that the amount of the adhesive adhered onto the porous thin supporting paper was about 2 g'. per square meter in terms of the solid content of the adhesive; An' original carrying a printed image (in this case, a newspaper) was superposed on the surface of the film of the thus prepared stencil sheet, and infrared-ray irradiation was applied (by employing a Thermofax copying machine manufactured by 3-M Co., Ltd.) to the surface of said porous thin supporting paper, thereby effecting the perforation. As a result, there was formed a distinct darkbrown image onvthe perforated area of the 'stencilyand it was possible to easily effect perforations congruent'or coextensive with the original image. Further, when said stencil was employed for printing with a commercialized mimeographic machine, it proved capable of producing a multiplicity of clear-cut prints which faithfully, reproduced the original image.

Determination of the appropriate amount of infraredray irradiation was made possible by observing theperforated image formed onto the stencil sheet by the process of irradiation with the unaided eyes, and, whenever the perforated image was short of clarity, the irradiation was repeated accordingly. Thus, it was found that the appropriate amount of irradiation in case ofprocessing an original of A-4 size superposed onto the stencil sheet was about 4 sec. irradiation.

For the purpose of comparison, 4 kinds of stencils were prepared by employing 4 pieces of a stencil sheet obtained by merely affixing the foregoing film and porous thin sup porting paper, superposing an original of A-4 size carrying a printed image on the respective pieces, and subjecting them to irradiation with infrared rays by means of the foregoing Thermofax copying machine for about 3 sec., 4 sec., 5 sec. and 6 sec. respectively. In case of these .4 stencils, the perforated images formed onto each stencil were almost illegible and it was impossible to judge which was properly exposed. And, when said stencils were respectively employ for printing with a commercialized mimeographic machine,-the prints obtainedby' employing a stencil prepared by exposing to about4 s'ecirradiation was capable of faithfully representing the original image, but allthe remaining stencilsproduced indistinct prints.

Example 2 v 10 g. of fructose was dissolved in a mixed solution. consisting of 15 cc. of methanol and 1 cc. of methyl Cellosolve, and into the solution thus obtained was added and thoroughly mixed 1.5 cc. of undiluted sulfuric acid. The resultant solution was applied onto a 7,:r-thick, transparent film comprising vinylidene chloride-vinyl chloride copolymer as its principal component and was dried, thereby forming a coating of visibly reactive heat-sensitive component. Subsequently, byemploying an adhesive Gohsenyl M-50 Y-S adjusted to have'a viscosity of 8 centipoises with methanol, and afiixing a porous thin supporting paper similar to that of Example 1, through the same operation as Example 1, onto a surface of the aforesaid film where the formation of a coating of the visibly reactive heat-sensitive component was not elfected, a heat-sensitive stencil sheet was prepared.

When the thus prepared stencil sheet was subjected to infrared-"rayirradiation in the same manner as in Example 1, there' was obtained a stencil carrying a clear-cut, dark brown and legible perforated image and suitable for use in m'imeographic printing. Besides, the perforation work in this case was as easy as in Example 1. Further, when said stencil was employed for printing with a commercialized mimeographic machine, it was, capable of producing a multiplicity of prints having a clear-cut image.

' Example 3 By dissolving 7g. of primary cobalt acetate and 1.5 g. of thiourea in cc. of methanol, a solution of visible reactive heat-sensitive component was prepared. Subsequently, a compound sold under the trade name SUPER DAIN -FB comprising a polyacryl resinas its principal component was adjusted to have a viscosity of $8 centipoises with methanol and was mixed with its equivalent of the foregoing visibly reactive heat-sensitive component solution, whereby an adhesive containing the said component was prepared. Then, by aflixing a porous thin supporting paper similar to that employed in Example ,1 onto a film by conventional bonding method, a heat-sensitive stencil sheet was prepared.

The thus prepared stencil sheet proved capable of facilitating the determination of an appropriate value of infrared-ray irradiation at the time of preparing the stencil. Besides, when employed for printing, the stencil produced a multiplicity of prints faithfully representing the original image.

Example 4 By adding 25 g. of a 50%-alcohol solution of vinyl acetate polymer (in this case, Gohsenyl M-SO Y-S) and cc. of methanol into a solution consisting of 3.0 g. of lead acetate, 5.0 g. ofvthiourea and 0.5 g. of Krehalon-SN, and mixing them Within a ball mill, an adhesive containing the visiby reactive heat-sensitive component 'was prepared. Subsequently, a' 6/.L-thl0k, transparent film comprising vinylidene chloride-vinyl chloride copolymer as its principal component was affixed onto a porous thin supporting paper similar to that employed in Example 1 with said adhesive whereby there was obtained a heat-sensitive stencil sheet. In this connection, when infrared-ray irradiation was applied through the same operation asin Example 1, a clear-cut, dark brown and legible perforated image was formed, whereby. the

perforation was performed very easily. Further, when the thus prepared stencil was employed for printing with a commercial mimeographic machine, it was capable of producing a multiplicity of such prints faithfully rep resenting the original image.

Example By employing combinations of visibly reactive heatsensitive components, solvents and adhesives as shown in the following table, heat-sensitive stencil sheets of the typeof Example 1 and the type of Example 2 were respectively prepared in accordance with those manners of operation, described in the respective examples.

Color tone of Visibly reactive heat-sensitive component Adhesive Solvent image Hexamethylene-tetramine and cobalt chloride Polyvinyl acetate Methanol Blue. Benzoin-lead acetate and'suliur... do Dark brown. Ferric stearate and gallle acid... n n Do. Zinc stearate and diphenylcarbazone. do Red. Lead oxalate and thiourea Polyacrylie resin ..-..do Dark brown. 1 Silver stearate and protocatechinie acid.-.. .do Do, 1 Ferric laurate and thiosernicarbazide Polyvinyl acetate .do Do. 1 Copper stearate and dlalkyl-zinc dithiocarbamatedo D 2 Diphenyl-nltrosoamlne and protoeatechinic acid. do do Do.

What we claim is:

1. A heat-sensitive stencil sheet consisting essentially of a porous thin supporting paper layer capable of transmitting a fluent ink therethrough, said paper layer having bonded to one surface thereof, by an intermediate adhesive layer, a thin thermoplastic film layer having a thickness in the range of from S to 10,u and capable of being perforated when heated to a temperature in the range of about 120 to 170 C. by heat from infrared radiation absorbed by image areas on an original placed in heatconductive contact with the outer face of said film layer, said film layer consisting essentially of a thermoplastic synthetic resin selected from the group consisting of vinylidene chloride-vinyl chloride copolymer, polystyrene, polypropylene and polyethylene, said adhesive layer consisting essentially of an adhesive containing mixed therein a heat-sensitive component capable of reacting to form a visible image corresponding to the image areas on said original, when heated by the heat absorbed by the image areas of the original simultaneously with the formation of the perforated image areas in said film layer, the amount of said heat-sensitive component contained in said adhesive being in the range of from 0.3 to 4.0 parts by weight per one part by weight of said adhesive and the amount of the mixture consisting of said adhesive and said heat-sensitive component being in the range of from 1.5 to 10 g. per m9 of the surface of said paper layer.

2. A heat-sensitive stencil sheet according to claim 1, wherein said porous thin supporting paper layer has a weight in the range of from 7 to 14 g. per m2 3. A heat-sensitive stencil sheet according to claim 1, in which said heat-sensitive component is selected from the group consisting of (1) a complex compound of hexamethylenetetramine and a compound selected from the group consisting of cobalt chloride, cobalt iodide, cobalt bromide, nickel chloride, nickel bromide, cobalt nitrate, cobalt sulfate, nickel nitrate and nickel sulfate;

(2) a mixture of (a) a compound having a secondary alcoholic hydroxyl radical selected from the group consisting of benzoins, carbinols, phenolic compounds and aliphatic polyhydric alcohols, (b) sulfur and (c) metal inorganic salts or metal acetates;

(3) a mixture of said compound 2(a), sulfur and said compound 1;

(4) a mixture of a carbohydrate and a dehydrating agent;

(5) a mixture of (a) an iron salt of a fatty acid and (b) phenol or a phenolic compound;

(6) a mixture of (a) a heavy metal salt of an organic acid and (b) an alkaline earth metal sulfide, diphenylcarbazide or diphenylcarbazone;

(7) a mixture of (a) a heavy metal oxalate and (b) sodium tetrathionate, sodium thiosulfate or thiourea;

(8) a mixture of (a) a ferric salt of a fatty acid and (b) an aromatic polyhydroxy compound;

(9) a mixture of (a) a noble metal salt of an organic acid and (b) an organic polyhydroxy compound;

(10) a mixture of (a) a noble metal salt of an organic acid and (b) protocatechuic acid, spiroindane and hydroquinone;

(11) a mixture of (a) an iron salt of a fatty acid and (b) thiosemicarbazide or isothiosemicarbazide;

(12) a mixture of (a) a lead salt of an organic acid and (b) a thiourea derivative;

(13) a mixture of (a) a heavy metal salt of a higher fatty acid and (b) zinc dialkyldithiocarbamate; and

(14) a composition that forms an oxazine dye or an azo dye.

i. A heat-sensitive stencil sheet consisting essentially of a porous thin supporting paper layer capable of transmitting a fluent ink therethrough, said paper layer having bonded to one surface thereof a thin thermoplastic film layer having a thickness ranging from 5 to 10 and capable of being perforated when heated to a temperature in the range of about C. to C. by heat from infrared radiation absorbed by image areas on an original placed in heat-conductive contact with the outer face of said film layer, said film layer consisting essentially of a thermoplastic synthetic resin selected from the group consisting of vinylidene chloride vinyl chloride copolymer, polystyrene, polypropylene and polyethylene, said film layer being bonded to said paper layer by an intermediate adhesive layer, and a coating formed on the outer face of said film, said coating consisting essentially of a heatsensitive component capable of reacting to form a visible image corresponding to the image areas on said original, when heated by said heat absorbed by image areas of the original simultaneously with the formation of the perforated image areas in said film, said coating being applied at a rate of 0.5 to 10 g. of said heat-sensitive component per m? of said film.

5. A heat-sensitive stencil sheet according to claim 4, wherein said porous thin supporting paper has a weight in the range of from 7 to 15 g. per m? 6. A heat-sensitive stencil sheet according to claim 5, in which said heat-sensitive component is selected from the group consisting of (1) a complex compound of hexamethylenetetramine and a compound selected from the group consisting of cobalt chloride, cobalt iodide, cobalt bromide, nickel chloride, nickel bromide, cobalt nitrate, cobalt sulfate, nickel nitrate and nickel sulfate;

(2) a mixture of (a) a compound having a secondary alcoholic hydroxyl radical selected from the group consisting of benzoins, carbinols, phenolic compounds and aliphatic polyhydric alcohols, (b) sulfur and (0) metal inorganic salts or metal acetates;

(3) a mixture of said compound 2(a), sulfur and said compound 1;

(4) a mixture of a carbohydrate and a dehydrating agent;

(5) a mixture of -(a) an iron salt of a fatty acid and (b) phenol or a phenolic compound;

(6) a mixture of (a) a heavy metal salt of an organic acid and (b) an alkaline earth metal sulfide, diphenylcarbazide or diphenylcarbazone;

(7 a mixture of (a) a heavy metal oxalate and (b) sodium tetrathionate, sodium thiosulfate or thiourea;

(8) a mixture of (a) a ferric salt of a fatty acid and (b) an aromatic polyhydroxy compound;

(9) a mixture of (a) a noble metal salt of an organic acid and (b) an organic polyhydroxy compound; (10) a mixture of (a) a noble metal salt of an organic acid and (b) protocatechuic acid, spiroindane and hydroquinone; (11) a mixture of (a) an iron salt of a fatty acid and (b) thiosemicarbazidc, or isothiosemicarbazide; (12) a mixture of (a) a lead salt of an organic acid and (b) a thiourea derivative; (13) a mixturcof (a) a heavy metal salt of a higher fatty acid and (b) zinc dialkyldithiocarbamate; and (14) a composition that forms an oxazine dye or an azo dye.

References Cited UNITED STATES PATENT Tate etyal. ,1 17-36..7 X Clark et a1; ......2 11 7-36.7X Sorensen 117-369 X Wingert et a1. -11736.7 X

Wartrnan et al, a

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 682 763 Dated August 8, 1972 Inventofls) Keishi Kubo and Kiyoshi Sakai It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 44; change "7 to 14" to -7 to l5--.

Column 10, line 34; change "chloride vinyl" to -chloride vinyl-.

Column 10, line 49; change Claim 5" to Claim 4--.

Signed and sealed this 9th day of January 1973..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-1050(10-69) USCOMM-DC 60376-P69 a u.s. GOVERNMENT PRINTING OFFICE: uses o-ass-aaa 

